Could also be a flying promotional bearskin bladder from a local hunting lodge.

Which I have to say is where we may start to see a tragic lack of creativity unfolding on China's part.

Dang, you're correct. It still had a thermal signature, but it wasn't as definitive as what I thought.

If it was not a drone, and "not a balloon", what could it be?

Assuming this was a drone, the "car-sized", "unmanned", "not a balloon", "not maneuverable" (!?), the operating altitude (40k feet / 13 km), and use of AIM9X (IR/heat seeking) should narrow down the possible drones.

Also, one thing I pondered: why F22 instead of F35 to shoot it down? Maybe a question of availability. But, at least publically the F35 operating ceiling is lower than F22, so I was thinking whether the object was in reality higher than the publically known F35 operating ceiling.

> If it was not a drone, and "not a balloon", what could it be?

It could be an unmanned glider with some solar power. Several companies make those. Including Google, which was considering them as data relays back around 2016.

The F22 is America's superiority fighter, still beating the F35 in stealth and capability for anti flying things action. The F22 will probably be the default in most intercept circumstances.